Rock anchor

ABSTRACT

A system including a chemical rock anchor and a device for injecting a fixative, the rock anchor including an anchor tube enclosing a cavity. The device includes at least one holding chamber containing the fixative, a tube into which the at least one holding chamber is integrated, permits injection of a fixative into a space between an anchor tube and a hole that has been drilled into the rock, while requiring little technical effort and permitting a controlled process. The tube can be inserted into the cavity, and/or the tube and the anchor tube are separate parts, and/or the tube is not attached to the anchor tube, and/or the system does not include any fastening means for the bonding and/or non-positive fastening of the tube to the anchor tube.

This claims the benefit of German Patent Appliatino DE 10 2011 078 769.0, filed Jul. 7, 2011 and hereby incorporated by reference herein.

The present invention relates to a system comprising a chemical rock anchor, especially for use in mining, and to a device for injecting a fixative, to a method for affixing a rock anchor in rock, and to a device for injecting a fixative into a space between an anchor tube and a drilled hole.

BACKGROUND

Rock anchors are employed in mining and tunnel digging in order to prevent and to slow rock movement of the bedrock, or to secure large-scale spalling of the bedrock, so as to allow safe operation. Two functional principles are known in this context, which at times are also combined with each other. In the case of mechanical systems, the anchor is bolted by means of frictional locking, whereby mechanical stone or rock anchors usually also have an expansion sleeve. In the case of chemical rock anchors, anchor tubes with a curing mortar or with synthetic resin as the fixative are bonded to the substrate or to the bedrock. In this case, the rock anchors are set in the rock with or without pre-tensioning. Rock anchors in mining, for example, in underground coal extraction—in contrast to applications in tunnel digging—are only employed to stabilize the rock temporarily since generally speaking, the temporarily stabilized rock is going to be mined in a later work procedure, and consequently, the rock anchor is removed again from the rock.

Self-drilling rock anchors are fitted with a drill head on the back end of the rock anchor. Such self-drilling rock anchors can be drilled into the rock in one step and subsequently anchored, without the need for an additional drilling step using a separate drilling tool. In the case of rock anchors without a drill head, a drill rod has to be used in a first step in order to drill a hole into the rock, after which the rock anchor without a drill head can be inserted into the drilled hole.

The fixative, for instance, a synthetic resin having an adhesive component and a curing component, can be injected in different ways into an annular space between the rock and the rock anchor or the anchor tube. After a hole has been drilled into the rock, two cartridges containing the adhesive component and the curing component are inserted into the drilled hole. Subsequently, the anchor tube is inserted into the drilled hole, causing the cartridges to be destroyed by the anchor tube and the synthetic resin of the adhesive and curing components to be distributed in the annular space between the anchor tube and the rock. In another prior-art method, the adhesive and curing components are located in two cartridges or pouches inside a cavity enclosed by the anchor tube. After the anchor tube has been inserted into the hole that has been drilled into the rock, a piston is used to destroy the adhesive component cartridge and the curing component cartridge, after which a movement of the piston conveys the synthetic resin into the space between the anchor tube and the rock.

German laid-open document DE 10 2005 050 929 A1 discloses a method for setting of rock anchors in which an anchor rod having an internal channel is inserted into a drilled hole, then a flowable compound is pressed through the internal channel, and the ready-made drilled hole is filled with the compound, after which the compound cures in the drilled hole together with the anchor rod that is left behind in the drilled hole.

German laid-open document DE 31 00 730 A1 discloses a method that employs tubes that are fastened as stabilizing anchors in drilled holes in order to support and/or stabilize walls consisting of bedrock, brittle rocks or soil that are present in hollow spaces in underground construction, mining and tunnel digging. Here, the drilled hole has an inner diameter that is larger than the outer diameter of the tube, the tube is then inserted into the drilled hole where its inner end is secured, after which a two-component adhesive is injected into the drilled hole through the tube until the space between the outer wall of the tube and the wall of the drilled hole has been filled up.

German laid-open document DE 10 2009 002 951 A1 discloses a self-drilling fastening element for chemical anchoring in a substrate, which has a hollow cylindrical holding element with a drill head at one end. An internal tube is arranged inside the holding element, and a curable multi-component compound that can be pressed out is stored inside the internal tube.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system comprising a chemical rock anchor, especially for use in mining, a device for injecting a fixative, a method for affixing a rock anchor in rock, a device for injecting a fixative into a space between an anchor tube and a drilled hole, and by means of this system, the fixative can be injected into a space between the anchor tube and a hole that has been drilled into the rock while requiring little technical effort and permitting a controlled process.

The present invention provides a system comprising a chemical rock anchor, especially for use in mining, and comprising a device for injecting a fixative, whereby the rock anchor comprises an anchor tube that encloses a cavity, preferably an anchor nut, preferably an anchor plate that is supported by the anchor nut and that is to be placed into contact with the rock, said device comprising at least one holding chamber containing the fixative, a tube into which the at least one holding chamber is integrated, whereby the tube can be inserted into the cavity, especially after the anchor tube has been inserted into a hole that has been drilled into the rock, and/or the tube and the anchor tube are separate parts, and/or the tube is not attached to the anchor tube, and/or the system does not comprise any fastening means for the affixing step, especially for the bonding and/or non-positive fastening of the tube to the anchor tube. Therefore, this advantageously constitutes a two-part system consisting of the rock anchor and the device. Consequently, the device and the rock anchor can be stored separately and only one device is needed in order to inject the fixative for several rock anchors. This translates into cost savings since just a single device can be used for numerous rock anchors in order to inject the fixative into the space between the anchor tube and the rock.

In particular, the outer diameter of the tube essentially can match the diameter of the cavity. In essence, this means that the outer diameter of the tube matches the diameter of the cavity with a deviation of less than 30%, 20%, 10%, 5% or 2%.

In another embodiment, the device comprises at least one means for conveying the fixative outside of the tube into a space between the anchor tube and a hole that has been drilled into a rock when the tube that has been inserted into the cavity. Therefore, once the fixative contained in the holding chamber has been injected into the cavity enclosed by the anchor tube, the means for conveying the fixative can convey or inject the fixative into the space between the anchor tube and the hole that has been drilled into the rock.

In a supplementary embodiment, the at least one holding chamber is configured as at least one chamber delimited by the walls of the tube, as at least one cartridge or as at least one pouch. The holding chamber can thus be configured either as a separate part inside the tube, for instance, as a cartridge or as a pouch, or else the at least one holding chamber can be shaped, preferably in one piece, onto the tube in that additional walls are present on the tube. Preferably, the at least one holding chamber can be configured so that it can be refilled. The at least one holding chamber is therefore not destroyed, or else only partially, when the fixative is conveyed into the space between the anchor tube and the rock, or else the holding chamber is configured in such a way that this sort of destruction is not needed in order to discharge the fixative from the at least one holding chamber. For example, for this purpose, the volume of the holding chamber can be increased or decreased like an accordion. This means that the at least one holding chamber is not a disposable part.

Preferably, the at least one means is configured as a piston or as a plunger.

In one variant, the device comprises at least one means for mechanically, hydraulically or pneumatically moving the piston or the plunger, for example, a high-pressure pump and a sealing plate for the tube.

Advantageously, the fixative is a synthetic resin having an adhesive component and a curing component, and the adhesive and curing components are stored separately in two holding chambers.

In another embodiment, the system, especially the device, comprises a mixing element for mixing the fixative, and/or the device comprises a magazine containing several tubes, and/or the rock anchor comprises a drill head on a back end of the anchor tube. The magazine is arranged, for example, on a drilling cart for automatically injecting the fixative. Thus, for instance, several holes are drilled into the rock, after which the rock anchors are inserted into these drilled holes. Several tubes for the magazine can subsequently inject the fixative into the rock anchors very quickly one after the other. In this context, different types of fixatives are arranged on the magazines, so that different types of fixatives that are suitable for the bedrock in question can be injected into the drilled hole.

Advantageously, the anchor tube is configured as a hollow tube.

The inventive method for affixing a rock anchor into rock, especially with a system described in the present patent application, comprises the following steps: drilling a hole into the rock, inserting the rock anchor into the drilled hole, storing a fixative in at least one holding chamber, especially in that the at least one holding chamber is integrated into or arranged in a tube, preferably the tube is arranged inside a cavity enclosed by the anchor tube, conveying a fixative into a space, especially an annular space, between an anchor tube and the rock, bonding the anchor tube with the fixative to the rock, curing the fixative, whereby, after the fixative has been conveyed into the space between the anchor tube and the rock, the tube and/or the at least one holding chamber is pulled out of the cavity that is enclosed by the anchor tube. The tube and/or the at least one holding chamber can thus be employed for a wide array of anchor tubes and is not left behind in the anchor tube after the fixative has cured.

In particular, while the fixative is being injected into the cavity, it does not flow, and/or, while the fixative is being conveyed, it flows into the space between the anchor tube and the rock, and/or the fixative, which was at first stored in at least one holding chamber, is injected into a cavity enclosed by the anchor tube, and subsequently, the fixative is conveyed into the space between the anchor tube and the rock, and particularly while the fixative is being injected into the cavity, the anchor tube is arranged in the drilled hole, and/or the anchor tube has been inserted into the drilled hole. The fixative is thus not pumped into the cavity enclosed by the anchor tube, so that the fixative does not reach the cavity by flowing there. Rather, the fixative is stored inside the at least one holding element and the holding chamber is inserted into the cavity.

In another embodiment, the fixative is injected into the cavity in that at least one holding chamber, especially one that is integrated into or arranged in a tube, is inserted into the cavity; in particular, the tube is inserted into the cavity while the anchor tube is already arranged in the drilled hole.

In a supplementary variant, the fixative is conveyed out of the at least one holding chamber into a space between the anchor tube and a hole drilled into the rock, by at least one means for conveying the fixative, especially by means of a mechanically, hydraulically or pneumatically moved piston or plunger.

In another variant, the fixative is configured as a synthetic resin having an adhesive component and a curing component, and the adhesive and curing components, which are stored separately in two separate holding chambers, are injected into the cavity, and, while the fixative is being conveyed into the space between the anchor tube and the hole that has been drilled into the rock, the adhesive component and the curing component are mixed together in a mixing element.

In another embodiment, the at least one holding chamber, especially configured as a cartridge or pouch, is destroyed by the means for conveying the fixative, especially after introduction into the cavity, and/or the drilled hole is created by a separate drill rod or by the rock anchor fitted with a drill head.

An inventive device for injecting a fixative into a space between an anchor tube and a drilled hole, comprising at least one holding chamber containing the fixative, preferably at least one means for conveying the fixative into a space between the anchor tube and a hole that has been drilled in the rock, whereby the at least one holding chamber is configured inside a tube, so that the tube can be inserted into a cavity enclosed by the anchor tube after the anchor tube has been inserted into the drilled hole, especially several tubes are arranged in a magazine, and/or the fixative can be conveyed by the at least one means when the tube is arranged in the cavity.

The rock anchor is also configured as a sliding anchor. The sliding anchor has a sliding function to the effect that, starting at a prescribed tensile force absorbed by the rock anchor, that is to say, the compressive force which is being exerted onto the anchor plate or anchor nut and which is caused by the rock, the length of the rock anchor increases, as a result of which movement on the rock is allowed, which reduces the tensile forces to be absorbed by the rock anchor (below the tensile force prescribed as the threshold value, so that the anchor no longer slides), thus ensuring that the rock is more effectively stabilized.

In an additional embodiment, a back end of the anchor tube is closed off by a cap, and the anchor tube and/or the cap have at least one opening to carry the fixative out of the cavity enclosed by the anchor tube. On the one hand, the cap can be a separate part or, on the other hand, it can also be configured in one piece together with the anchor tube.

In a supplementary embodiment, the fixative, especially a synthetic resin or mortar, consists of two components, for instance, an adhesive component and a curing component.

In a supplementary embodiment, the components of the system, for example, the anchor tube, the tube, the piston, the anchor nut, the anchor plate, the cap, are all made, at least partially, especially completely, of metal, e.g. steel or a steel alloy, or else of fiberglass-reinforced plastic.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described in greater detail below making reference to the accompanying drawings. The following is shown:

FIG. 1: a longitudinal section of a rock anchor after it has been inserted into a drilled hole,

FIG. 2: a longitudinal section of a rock anchor according to FIG. 1 after a tube having two holding chambers for the fixative has been inserted into a cavity enclosed by an anchor tube of the rock anchor,

FIG. 3: a longitudinal section of a system according to FIG. 2 after the fixative has been conveyed into a space between the anchor tube and a rock, and

FIG. 4: the rock anchor according to FIG. 1 after the fixative has cured.

DETAILED DESCRIPTION

A rock anchor 2 configured as a sliding anchor is employed, for example, in mining operations, in order to temporarily stabilize rock 28 in tunnels. The rock anchor 2 comprises an anchor tube 4 that encloses a cavity 15. The rock anchor 2 is a chemical rock anchor 2, that is to say, the anchor tube 4 can be bonded to the rock 28 by means of a fixative 16. For this purpose, a hole 29 has to be drilled into the rock 28 by means of a drilling rod and subsequently, the rock anchor 2 can be inserted into the drilled hole 29, together with the anchor tube 4 (FIG. 1).

FIG. 4 shows the rock anchor 2 fastened with the fixative 16. The anchor tube 4 has an outer thread 12 on the outside, and an anchor nut 13 having an inner thread is screwed onto the outer thread 12 of the anchor tube 4. In this process, the inner thread of the anchor nut 13 engages with the outer thread 12 of the anchor tube 4. The anchor nut 13 has a polygon on the outside. Via this polygon located radially on the outside of the anchor nut 13, a torque can be transferred to the anchor nut 13 and the anchor nut 13 can be screwed onto the anchor tube 4 all the way to the position depicted in FIG. 4. The anchor nut 13 rests indirectly via an anchor plate 14 on the rock 28, so that the rock 28 can be stabilized with the rock anchor 2. The compressive forces transferred from the anchor nut 13 to the anchor tube 4 are transferred from the anchor tube 4 with the fixative 16 to the rock 28.

A system 1 (FIGS. 2 and 3) comprises, aside from the rock anchor 2, also a device or injector 3 for injecting the fixative 16 into a space 26, especially an annular space 27, between the anchor tube 4 and the rock 28 or the drilled hole 29. The device 3 comprises a tube 5 inside of which a mixing element 9 and two holding chambers 6, namely, a first pouch 7 and a second pouch 8, are arranged. The first pouch 7 holds or stores an adhesive component 18 of a synthetic resin 17, while the second pouch 8 holds or stores a curing component 19 of the synthetic resin 17 (FIG. 2). The mixing element 9 closes off a back end area of the tube 5 while a front end area or a front end of the tube 5 is closed off by a sealing plate 24 that has an opening 25. The anchor tube 4 has a back end 11 and a front end 10. At the back end 11 of the anchor tube 4, a cavity 15 enclosed by the anchor tube 4 is closed off by a cap 22, the latter having an opening 23. The fixative 16 can be introduced into the space 26 through the opening 23. A drill head 111, shown schematically, may or may not be present at back end 11.

Moreover, the device 3 is provided with a means 21 for conveying the fixative 16 into the space 26. The means 21 here comprises a piston 20 and the sealing plate 24. In addition, the means 21 comprises a high-pressure pump P (shown schematically) for injecting pressurized water at a high pressure through an opening 25 in the sealing plate 24.

After the hole 29 has been drilled into the rock 28, the anchor tube 4 of the rock anchor 2 can be inserted into the drilled hole 29 (FIG. 1). Once the rock anchor 2 has been inserted into the drilled hole 29, the tube 5 of the device 3 is inserted into the cavity 15 enclosed by the anchor tube 4 (FIG. 2). Diverging from this, the tube 5 can already be inserted into the cavity 15 before the anchor tube 4 is inserted into the drilled hole 29. Subsequently, the high-pressure pump injects pressurized water at a high pressure through the opening 25 into a space enclosed by the tube 5. This causes the piston 20 that is depicted in FIG. 2 to move upwards in the axial longitudinal direction of the anchor tube 4 or of the tube 5 (FIG. 3), causing the first and second pouches 7, 8 containing the adhesive component 18 and the curing component 19 to be destroyed, and the synthetic resin 17 of the adhesion and curing components 18, 19 is conveyed through the mixing element 9 and subsequently through the opening 23 into the space 26 between the anchor tube 4 and the drilled hole 29, so that here the synthetic resin 17 flows into the annular space 27. However, the fixative 16 does not flow while the fixative 17 contained in the tube 5 is being injected into the anchor tube 4. The mixing element 9 is arranged inside the tube 5, so that all of the synthetic resin 17 has to flow through the mixing element 9 before exiting through the opening 23. In this process, the mixing element 9 is equipped with mixing implements of a type, for instance, that have an appropriate geometry, so that the fixative flows in a meandering or spiral pattern through the mixing element 9, thus ensuring a very effective and thorough mixing of the adhesive component 18 and the curing component 19. After the fixative 16 has been conveyed into the space 26 or after the fixative 16 had been pressed into the space 26, the tube 5 is once again pulled out of the cavity 15 that is enclosed by the anchor tube 4 (FIG. 4), so that only the rock anchor 2 remains in the drilled hole 29 after the fixative 16 has cured.

All in all, the inventive system 1 and the inventive method for affixing the rock anchor 2 entail major advantages. The device 3 and the rock anchor 2 are two separate parts, so that just a single device 3 can be used for numerous rock anchors 2 in order to inject the fixative 16 into the space 26. For this purpose, all that is necessary is for the devices 3 to be pushed into the rock anchor 2 one after the other after the rock anchor 2 has been inserted, as depicted in FIG. 2. The holding chambers 6 inside the tube 5 can be configured so that they can be refilled, thus dispensing with the need for a costly replacement of holding chambers 6 that would be configured, for example, in the form of disposable pouches 7, 8. It is likewise possible to store a plurality of devices 3 in a magazine 100, shown schematically in FIG. 2, of a drilling cart, so that the fixative 16 for numerous rock anchors 2 can be quickly conveyed into the space 26. The tubes 5 of the device 3 can also be considerably longer than the anchor 4, thus allowing the tube 5 to also be used for different anchors 4 of different lengths. Moreover, different types of fixatives 16 can be kept on hand on the tube 5, especially in the case of a plurality of tubes 5, especially in the case of a magazine, for instance, on a drilling cart, so that the most suitable fixative 16 can then be injected into the space 26 as a function of the specific rock 28 where the anchor tube 4 is located. Different fixatives 16 for different types of rock and/or different types of applications can be kept on hand on a drilling cart and then used. After the fixative 16 has been pressed out, the cavity enclosed by the anchor tube 4 stays empty. This translates into savings since the holding chambers 6 or the means 21, for instance, the piston 20, are not left behind in the anchor tube 4. Therefore, the rock anchor 2 is particularly inexpensive to produce since it does not include the holding chambers 6 and the means 21, for example, the piston 20, but rather, they can be employed on the device as separate parts and can preferably be reused for a wide array of rock anchors 2. 

1. A system comprising: a chemical rock anchor including an anchor tube enclosing a cavity; and an injector for injecting a fixative, the injector including at least one holding chamber containing the fixative, a tube, the at least one holding chamber integrated in the tube, at least system further including at least one of the following: the tube being insertable into the cavity; the tube and the anchor tube being separate parts; the tube not being attached to the anchor tube; and the system lacking a fastener for the bonding or non-positive fastening the tube to the anchor tube.
 2. The system as recited in claim 1 wherein the rock anchor is a mining rock anchor.
 3. The system as recited in claim 1 further comprising an anchor nut.
 4. The system as recited in claim 3 further comprising an anchor plate supported by the anchor nut for contact with the rock.
 5. The system as recited in claim 1 wherein the tube is insertable into the cavity after the anchor tube has been inserted into a hole drilled into the rock.
 6. The system as recited in claim 1 wherein the system lacks any fastener fastening the tube to the anchor tube.
 7. The system as recited in claim 1 wherein the outer diameter of the tube essentially matches the diameter of the cavity.
 8. The system as recited in claim 1 wherein the injector comprises a conveyor for conveying the fixative outside of the tube into a space between the anchor tube and a hole drilled into a rock when the tube has been inserted into the cavity.
 9. The system as recited in claim 1 wherein the at least one holding chamber is configured as at least one chamber delimited by the walls of the tube, as at least one cartridge or as at least one pouch.
 10. The system as recited in claim 8 wherein the conveyor includes a piston or a plunger.
 11. The system as recited in claim 10 wherein the device includes an actuator actuating the piston or plunger mechanically, hydraulically or pneumatically and further includes a sealing plate for the tube.
 12. The system as recited in claim 11 wherein the actuator is a high-pressure pump.
 13. The system as recited in claim 1 wherein the fixative is a synthetic resin having an adhesive component and a curing component, and the adhesive and curing components are stored separately in two holding chambers of the at least one holding chamber.
 14. The system as recited in claim 1 wherein at least one of the following is present: the system further includes at least one of a mixer for mixing the fixative; the injector includes a magazine containing several tubes; and the rock anchor includes a drill head on a back end of the anchor tube.
 15. The system as recited in claim 14 wherein the injector includes the mixer.
 16. A method for affixing a rock anchor into rock, comprising the following steps: drilling a hole into the rock; inserting the rock anchor into the drilled hole; storing a fixative in at least one holding chamber; conveying the fixative into a space between an anchor tube of the rock anchor and the rock; bonding the anchor tube with the fixative to the rock; curing the fixative; and after the fixative has been conveyed into the space between the anchor tube and the rock, at least one of a tube and the at least one holding chamber is pulled out of a cavity enclosed by the anchor tube.
 17. The method as recited in claim 16 wherein the at least one holding chamber is integrated into or arranged in the tube.
 18. The method as recited in claim 16 wherein the tube is arranged inside the cavity enclosed by the anchor tube.
 19. The method as recited in claim 16 wherein the space is an annular space.
 20. The method as recited in claim 16 wherein at least one of the following is present: while the fixative is being injected into the cavity, the fixative does not flow; while the fixative is being conveyed, the fixative flows into the space between the anchor tube and the rock; and the fixative, at first stored in the at least one holding chamber, is injected into the cavity and subsequently, the fixative is conveyed into the space between the anchor tube and the rock.
 21. The method as recited in claim 20 wherein while the fixative is being injected into the cavity, the anchor tube is arranged in the drilled hole, or the anchor tube has been inserted into the drilled hole.
 22. The method as recited in claim 16 wherein the fixative is injected into the cavity when the at least one holding chamber is inserted into the cavity.
 23. The method as recited in claim 22 wherein at least one holding chamber is integrated into or arranged in the tube.
 24. The method as recited in claim 22 wherein the tube is inserted into the cavity while the anchor tube is already arranged in the drilled hole.
 25. The method as recited in claim 16 wherein the fixative is conveyed out of the at least one holding chamber into the space by at least one conveyor for conveying the fixative.
 26. The method as recited in claim 25 wherein the conveyor is a mechanically, hydraulically or pneumatically moved piston or plunger.
 27. The method as recited in claim 16 wherein the fixative is configured as a synthetic resin having an adhesive component and a curing component, the adhesive and curing components being stored separately in two separate holding chambers of the at least one holding chamber and being injected into the cavity, and, while the fixative is being conveyed into the space between the anchor tube and the hole, the adhesive component and the curing component are mixed together in a mixing element.
 28. The method as recited in claim 16 wherein the at least one holding chamber is destroyed by a conveyor for conveying the fixative or the drilled hole is created by a separate drill rod or by the rock anchor fitted with a drill head.
 29. The method as recited in claim 28 wherein the at least one holding chamber is configured as a cartridge or pouch.
 30. The method as recited in claim 28 wherein the at least one holding chamber is destroyed after introduction into the cavity.
 31. The method as recited in claim 16 wherein a system is used to perform the method, the system comprising: a chemical rock anchor including an anchor tube enclosing a cavity; and an injector for injecting a fixative, the injector including at least one holding chamber containing the fixative, a tube, the at least one holding chamber integrated in the tube, at least system further including at least one of the following: the tube being insertable into the cavity; the tube and the anchor tube being separate parts; the tube not being attached to the anchor tube; and the system lacking a fastener for the bonding or non-positive fastening the tube to the anchor tube.
 32. A device for injecting a fixative into a space between an anchor tube and a drilled hole, the device comprising: at least one holding chamber containing the fixative; and at least one of the following: the at least one holding chamber is configured inside a tube, so that the tube can be inserted into a cavity enclosed by the anchor tube after the anchor tube has been inserted into the drilled hole; and a conveyor can convey the fixative in the case of the being tube arranged in the cavity.
 33. The device as recited in claim 32 further comprising the conveyor for conveying the fixative into the space.
 34. The device as recited in claim 32 wherein several tubes are arranged in a magazine. 